This study assesses and compares four product presentation formats currently used online: static pictures, videos without narration, videos with narration, and virtual product experi- ence (VPE), where consumers are able to virtually feel, touch, and try products. The effects of the four presentation formats on consumers’ product understanding as well as the moder- ating role of the complexity of product understanding tasks were examined in a laboratory experiment. Two constructs used to measure product understanding per- formance are actual product knowledge and perceived web- site diagnosticity (i.e., the extent to which consumers believe a website is helpful for them to understand products). The experimental results show that (1) both videos and VPE lead to higher perceived website diagnosticity than static pictures; (2) under a moderate task complexity condition, VPE and videos lead to the same level of actual product knowledge, but all are more effective than static pictures; (3) under a high task complexity condition, all four presentation formats are equally effective in terms of actual product knowledge. Moreover, the results also indicate that it is perceived website diagnosticity, not actual product knowledge, that affects the perceived usefulness of websites, which further influences consumers’ intentions to revisit the websites.